style(sce): remove inaccessible return statement
fix(*): protect calls to hasOwnProperty in public API

Objects received from outside AngularJS may have had their `hasOwnProperty`
method overridden with something else. In cases where we can do this without
incurring a performance penalty we call directly on Object.prototype.hasOwnProperty
to ensure that we use the correct method.

Also, we have some internal hash objects, where the keys for the map are provided
from outside AngularJS. In such cases we either prevent `hasOwnProperty` from
being used as a key or provide some other way of preventing our objects from
having their `hasOwnProperty` overridden.

Closes #3331